GM’s Fuel-Saving Technology Coming

General Motors has announced that the 2005 GMC Envoy XL, Envoy XUV and Chevrolet
TrailBlazer EXT will be the first vehicles to showcase GM’s innovative Displacement on
Demand fuel-saving technology. Displacement on Demand will be a standard feature in the
vehicles’ optional Vortec 5300 V-8 engine. The more efficient engine will boost the fuel
efficiency of these vehicles by about 8 percent (based on an EPA testing procedure). In
addition, GM previously announced it will introduce this technology as part of a new
overhead-valve V-6 family of engines in some 2006 midsize passenger cars. By 2008, more
than 2 million vehicles with the V-8 and V-6 engines will feature Displacement on Demand.
Both customers and the environment will benefit from the engines’ improved fuel economy. In
addition, GM owners won’t have to sacrifice superior engine performance and power to go
farther on a tank of gas. “Displacement on Demand will enhance fuel economy without
compromising performance or the ability to carry heavy loads,” said Sam Winegarden, GM
Powertrain chief engineer of Vortec V-8 engines. “We will be able to deliver the same
top-of-the-line performance with less effort and energy. That’s the essence of efficiency.”
Enabled by GM’s powerful electronic powertrain controls, Displacement on Demand saves fuel
by using only half of the engine’s cylinders during most normal driving conditions. When
loads are light, the control system automatically closes both intake and exhaust valves for
half of the cylinders, cutting off their air and fuel supply. The valves are reopened to
provide all-cylinder operation when the driver needs it for quick acceleration or for
hauling heavy loads. The V-8 engine always starts on eight cylinders, and in the case of
the V-6 engine, six cylinders. But once the vehicle has accelerated to speed, the
engine-control module activates Displacement on Demand, providing improved fuel economy
through a relatively inexpensive change in displacement to meet the vehicle-load
requirements.